Control arrangement for electric circuit breakers



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CONTROL ARRANGEMENT FOR ELECTRIC GIRCUT BREAKERS Filed NOV. 50 1944 Patented Sept. 19, 1950 CONTROL ARRANGEMENT FOR ELECTRIC CIRCUIT BREAKERS Alexander C. Boisseau and John W. Beatty, Lansdowne, Pa., assignors to General Electric Company, a corporation of New York Application November 30, 1944, Serial No. 565,833

Our invention relates to a control arrangement for electric circuit breakers, and particularly to a control arrangement for electric circuit breakers which are designed for reclosing operation.

Of recent years air blast circuit breakers employing the so-called retractable pin type contacts have been used extensively. 'I'he retractable pin type contacts form the arcing contacts and of course reclose as soon as the air blast is shut off. For this reason this type of-circuit breaker employs disconnecting or isolating contacts connected in series with the arcing contacts which disconnecting contacts are sequentially operated with the arcing contacts to maintain the circuit in the open condition once it has been interrupted, even when the arcing contacts reclose.

Such circuit breakers lend themselves very well for reclosing operation, for reclosing will automatically occur if the isolating contacts are not operated. Our invention is particularly concerned with a control arrangement for the above-mentioned type of fluid blast circuit breakers and is furthermore concerned with a pneumaticV reclosing relay which is adapted to be used with other forms of reclosing circuit breakers,

In retracting contact type breakers, the blast of fluid that is released, for example, in response to an abnormal line condition, first opens the arcng contacts thereby drawing an arc, then blasts the arc to extinction, after which it should maintain the contacts open for a brief period following interruption thereby preventing a possible restrike due to a high rate of rise of recovery voltage. Furthermore, should the contacts reclose while the abnormal line conditions still prevail, a successive blast should be initiated, in like lmanner to the preceding one; but in this event a somewhat longer blast may be required so that the arcing contacts are prevented from reclosing until the disconnecting contacts have separated sufficiently to effect a safe isolating gap in the line circuit. Obviously then, the blast durations are required to be precisely timed so that at least a suicient amount of fluid is released, while, on the other hand, no more than an adequate amount should .be released to fulflll the above requirements, because any un- V necessary prolongation oi the blast becomes excessively wasteful of pressure iluid.

13 claims. (ci. irs- 294) Known methods for timing and sequentially operating the blast valve and the arcing and isolating contacts for performing a reclosing and subsequent tripping operating cycle involve vaguely timed or complicated interlocking relaying devices that are liable to cumulative lnac. curacies.

Accordingly. it is an object of our invention to provide a new and improved reclosing control arrangement for electric circuit breakers.

It is another object of our invention to provide a pneumatic reclosing relay arrangement for electric circuit breakers, which is simple and compact, inexpensive to manufacture, and which gives accurate and positive control in every respect.

In the improved control arrangement of our invention, the pneumatic relay provides a unitary device that precisely governs and times with inevitable sequence the reclosing of the blast valve yto effect the reclosing of the arcing contacts,

the opening of the control circuit for an isolating switch interlock device, and the establishment of an alternate reopening circuit for the blast valve so as to effect the second interruption of the line and the subsequent opening ot the isolating contacts.

Further objects and advantages of our invention will become apparent as the following description proceeds and the features of novelty which characterize our invention `will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of our invention, reference may be had to the accompanying drawing in which Fig. 1 is a schematic diagram, partly in section, of a reclosing control arrangement embodying our invention with the circuit breaker in the closed position, and Fig. 2 is a schematic diagram of a portion of Fig. 1 illustrating the position of certain elements of our invention at a predetermined point during the reclosing cycle.

Although our invention is applicable to any fluid operated circuit breaker, we have chosen to specifically illustrate our invention in Fig. 1 as applied to an electric circuit breaker of the fluid operated, fluid blast type such as is disclosed in the copending application, Serial No. 565,834, now Patent No. 2,450,628, Boisseau, Beall, Frank and Lowery. filed concurrently with nozzle II.

the present application and assigned to the same assignee as the present application. Although a polyphase circuit breaker has been shown in the copending Boisseau, Beall, Frank and Lowery application referred to above we have chosen, for the purpose of simplifying the disclosure, to illustrate our invention in connection with a single phase circuit breakerv or one pole of a polyphase circuitbreaker.

Referring now to Fig. 1 of the drawing, there is illustrated an electric circuit breaker generally indicated at I comprising a pair of relatively moving arcing contacts 2 and 3 and a pair of relatively moving isolating or disconnecting contacts 4 and 5, serially arranged with respect to each other. The arcing contacts 2 and 3 have been illustrated as a part of a iluid blast interrupting unit 5 which may be constructed in the manner disclosed and claimed in copending application, Serial No. 570,006, Boisseau and Beall, illed December 27, 1944, now Patent No. 2,444,765, and assigned to the same assignee as the present application. Interrupting head or unit 5 comprises an insulating chamber 1 within which relatively movable arcing or interrupting contacts 2 and 3 are mounted. Both contacts 2 and 3 have been illustrated as movable contacts biased to the closed position by means of springs 3 and 3, respectively. In the closed position of the circuit breaker shown in Fig. 1, contacts2 and 3 are in electrical engagement and the contact 2 extends through a nozzle I while the contact 3 extends through a Associated with contact 2 is a iluld motor comprising the piston I2. Similarly associated with the contact 3 is a fluid motor comprising the piston I3. Pistons I2 and I3 are reciprocal within cylinders suitably mounted in arc extinguishing chamber 1.

In order to interrupt the current owing' through arcing contacts 2 and 3 fluid under pressure is supplied from a source illustrated as a' tank I4 through a blast conduit I5 to arcing chamber 1, conduit I5 being branched as indicated at I6 and I1 so as to supply fluid under pressure ahead of each nozzle I3 and II, respectively. The flow of this fluid under pressure which is preferably air, is controlled by a blast valve generally indicated at I8 closely associated with tank I4. When blast valve I3 is opened contacts 2 and 3 are retracted through nozzles I3 and II and a blast of fluid through each nozzle quickly extinguishes the arc drawn between contacts 2 and 3. The fluid blast exhausts to atmosphere through conduit I3.

Since arcing or interrupting contacts 2 and 3 are of the so-called retractable pin-type which reclose as soon as iluid under pressure is shut oi! relative to arclng chamber 1, it is necessary to provide isolating or disconnecting contacts 4 and 5. Isolating contact 4 is indicated as a stationary contact suitably supported on an insulating support and preferably electrically connected to a suitable circuit to be controlled as indicated at 2|. Disconnecting or isolating contact 5, on the other hand, really comprises an isolating switch or contact arm pivotally mounted about a horizontal axis 22. Isolating switch 5 is the movable contact and the pivoted end thereof is provided with a bevel gear 23 which meshes wlthbevel gear 24 mounted on a rotatable shaft 25. Shaft 25 is rotated from the grounded supporting structure below through an intervening insulating collumn 2S rotatable therewith.

Isolating contact arm 5 is electrically connected to movable arcing contact 3 by means oi' a con- 4 ductor 21. Y Movable arclng contact 2 is connected with power line or circuit 23 in order to control the power ilowing therein.

Blast valve I3 has been illustrated as comprising a valve member 23 connected by a valve stem 33 with the armature 3I of a solenoid including a winding 32. A suitable spring 33 normally biases valve member 23 to the closed position indicated in Fig. 1. Winding 32 for controlling the operation of blast valve I3 is connected to a source of control power 34 through the contacts 35 of an overload relay including a winding 35. Energization of winding 35 by a current oi' suiilcient magnitude will cause bridging of contacts 35 with the consequent energlzation of winding 32 of the blast valve solenoid from source oi' control potential 34. Winding 3i of the overload relay is connected to the secondary winding 31 of a current transformer associated with power line 23. In the eventof an abnormal current condition on power line 23, such as might be caused by a fault condition, winding 33 of the associated relay is energized suillciently to cause contacts 35 to close whereupon blast valve I8 is opened and an arc is drawn and extinguished in arcing chamber 1.

It is obvious that after arcing contacts 2 and 3 have operated to interrupt the circuit, isolating contacts 4 and 5 must be separated if the circuit is to remain open and this operation o! isolating contacts 4 and 5 must occur before arcing contacts 2 and 3 have reclosed. In order to cause relative separation of isolating or disconnecting contacts 4 and 5 we have provided a second iluid motor generally indicated at 33, the term second fluid motor being applied to distinguish it from the fluid motors in interrupting unit 5. Fluid motor 33 comprises a cylinder 33 having mounted therein a piston 43 which is connected by rod 4I with a rack 42. Rack 42 is adapted to engage a spur gear 43 mounted on rotatable insulating column 25. It is obvious from Fig. 1 that when piston 43 is moved to the left, shaft 25 and bevel gear 24 are rotated so as to move disconnecting arm 5 to its open position. Rack 42 may also be connected by a connecting rod 44 with another fluid motor in the manner disclosed and claimed in copending application Serial No. 529,670, Boisseau. illed April 5, 1944, now Patent No. 2,445,558, and assigned to the same assignee as the present application.

In order to operate iluid motor 33 and consequently to cause relative separation of Isolating or disconnecting contacts 4 and 5 cylinder 33 is connected with source I4 by conduits 45 and 43 and a switch controlling valve generally indicated at 41. Switch controlling valve 41, which is an opening valve, is preferably constructed in accordance with the arrangement disclosed and claimed in copending application Serial No. 565,835, now Patent No. 2,437,086, Frank and Kellar, tiled concurrently with the present application and assigned to the same assignee as the present application. Essentially, switch opening valve 41 comprises a main valve member 43 connected to a piston 43 and biased to the closed position by means of a spring 53. When the valve member 43 is in the closed position indicated in Fig. l, conduit 45 is connected to atmosphere through a port 5| which is closed by valve member 52 when valve member 43 is open. Opening valve 41 is of the balanced pressure type and is opened by operation of a pilot valve member 53 which opens the port 54 releasing to atmosphere the fluid under pressure acting on one side oi' the was . y l piston y48 with the consequent opening of valve member 48.

The pilot valve member 53 of circuit breaker opening valve 41 is illustrated as being pneumaticaliy operated by means of a. piston 55 connected thereto which piston is reciprocal in a cylinder 55. A spring 58 biases pilot valve member 53 of the circuit breaker opening valve 41 to the closed position.

Cylinder 55' `of the fluid motor for operating pilot valve member 53 is connected to blast valve conduit I5 by means of a conduit 61, isolating switch reclosing interlock valve, generally indicated at 58 to be described in greater detail hereinafter, rand conduit 58. Whenever blast valve I8 is open fluid under pressure will be admitted to conduit 51 and if isolating switch reclosing interlock valve 58 is open, as is indicated in Fig. l, this fluid under pressure may pass through conduit 59 into cylinder 55' with the consequent opening of pilot valve member 53. The opening of pilot valve member 53 causes opening of the main valve member 48 of circuit breaker opening valve 41 and fluid under pressure flows through conduit 45 to fluid motor 38. In accordance with the disclosure of the above mentioned Frank and Kellar copending application circuit breaker opening valve 41 is preferably provided with means for maintaining the valve in the open position once it has opened until the isolating contacts 4 and 5 have opened. Since this forms no part of our invention it has been omitted for the purpose of simplifying the drawings.

As was mentioned above, a circuit breaker having serially connected interrupting and isolating contacts in which the interrupting contacts are fluid operated and normally biased to the closed position is inherently adapted to operate as a reclosing circuit breaker since the interrupting contacts automatically reclose upon cessation of the fluid blast. Accordingly, we have provided a control arrangement by means of which the circuit breaker I may be operated as a reclosing breaker. It will be understood by those skilled in the art that reclosing operation of the circuit breaker I may be obtained by preventing the isolating contact arm 5 from operating whereupon interrupting contacts! 2 and 3 associated with interrupting unit 6 will interrupt the circuit and then will immediately reclose upon cessation of the interrupting blast.

In order to prevent contact arm 5 from openingr whenever blast valve I8 is caused to open we have provided isolating switch reclosing interlock valve 58 which controls the operation of switch opening valve 41. Isolatlng switch reclosing interlock valve 58 comprises a normally open valve member 68 slidably mounted in a housing 6I and adapted to be electrically operated by a solenoid 62 including a winding 63. Whenever winding 63 is energized valve member 60 moves upwardly to block the flow through interlock valve 58 and consequently to switch opening valve 41. Solenoid 62 may, if desired, control a switch 64 which normally bridges contacts 65, the purpose of which will be described later.

By employing a normally open interlock valve 58 instead of one which normally blocks the passage to the switch opening valve 41 and which is arranged to be moved to its open position after a predetermined number of reclosures to effect a full switch opening operation, it will be apparent that our arrangement has the advantage that should the interlock valve or its winding be inadvertently damaged 4and rendered inoperative, the breaker will simply effect a full switch opening operation in response to either a transient or sustained fault; whereas, in the case of the other mentioned arrangement. a damaged or frozen valve would preclude a full switch opening operation and serious damage to the equipment could ensue.

The reclosing-trip operation oi.' a circuit breaker consists of two successive openings of interrupting contacts 2 and 3 followed by opening of the isolating contacts. It will be understood that the interrupting contacts might be opened and reclosed more than two times before the isolating contacts are opened. However, we

prefer to provide only two successive operations of the interrupting contacts before the isolating contacts are operated, and to this end there is provided in accordance with our invention a pneumatic reclosing relay generally indicated at 66. This pneumatic reclosing relay controls the time which is permitted to elapse between the opening and reclosing of the interrupting contacts and furthermore conditions the reclosing control circuits for the opening operation of the isolating switch comprising contact arm 5 that sequentially follows the first reclosing operation if a persistent fault is present. Actually, pneumatic reclosing relay 66 performs four separate functions. First, it deenergizes the blast valve winding 32 by opening a normally closed switch 61 whereby the interrupting contacts 2 and 3 may reclose in response to a cessation of the fluid blast. Secondly, pneumatic reclosing relay 66 assures the establishment of a supplementary circuit for reenergizing blast winding 32 by closing a normally open switch 68, which is parallel or shunt with switch 61, within the short time interval ybetween the instant when switch 61 deenergizes the blast valve winding 32 and before the arcing contacts reclose. With this arrangement if a fault persists the blast valve winding 32 will immediately be reenergized, the blast valve opened and the arcing contacts operated to reinterrupt the circuit if overcurrent relay contacts 35 reclose. Thirdly, the pneumatic reclosing relay 66 assures that the isolating switch 5 is operated following a second quick successive opening operation of interrupting contacts 2 and 3 by opening a normally closed switch 69 which prevents reenergization of isolating switch reclosing interlock winding 63. Fourthly, the pneumatic reclosing relay 66 must restore the switches 61, 68 and 69 to their normal position indicated in Fig. 1 at the end of the .pneumatic reclosing relay cycle, say approximately one second, in preparation for a possible repeat reclosing cycle.

Before describing the detailed features of the pneumatic reclosing relay 66, the electrical circuits controlled by switches 61, 68 and 69 will be described whereby the operation of pneumatic reclosing relay 66 may be understood more readily. The winding 32 of blast valve I8, the energization of which is controlled by the bridging of contacts 35, is actually connected in series with two switches, the opening of either being effective to cut off the blast valve winding circuit. The first of these is switch 61, of the reclosing relay 66, the opening of which determines the duration of the first blast, while the second is the auxiliary or cut-off switch 18 whose opening deenergizes the supplementary blast valve winding circuit and which determines the longer duration of the successive blast. To

assassin those skilled in the art it will be understood from the above description that the closing of contacts 33 of the overload relay 33 merely initiates the opening of the blast valve due to the energization o! coil 32 and that the precise closing instant of the blast valve is governed alternatively either by the opening of the cut-oi! switch 31 or by the opening of auxiliary cut-oi! switch 13. Therefore suitable means, not shown but examples of which are well known in the art, are provided for insuring that after the circuit of winding 32 has been completed by the closing of contacts 33 of relay 33, the subsequent opening of these contacts 33 does not eiect the deenergization of the winding 32 until its circuit is opened either by the cut-off switch 31 or 13. It will be obvious from Fig. l that the circuit for energizing blast valve winding 32 may be traced from the positive side of potential source 34, through contacts 1I of auxiliary or cut-oi! switch 13', through switch 31 which normally engages contact 12, through blast valve winding 32 and the contacts 35 of the overload relay having a winding 36 to the negative terminal of control potential source 34.

A manually operated reclosing selector switch 13 is provided, which in the position indicated in Fig. 1 causes circuit breaker I to operate as a reclosing breaker. When in this position reclosing selector switch 13 compels winding 33 oi isolating interlock valve 33 to be energized from source 34 upon closure or bridging of contacts 33. The energization circuit for winding 33 may be traced from the positive terminal of source 34 through switch 33 which normally engages contact 14, winding 33 of isolating interlock valve 33, reclosing selector switch 13, and contacts 35 of the overcurrent relay including winding 33 to the negative terminal of potential source 34. As long as winding 33 is energized the associated valve member 33 prevents operation of the switch controlling valve 41 so that isolating switch 3 remains closed and only the arcing contacts 2 and 3 are operated. On the other hand, when selector switch 13 has been moved to its other position so as to engage contact 15, the control circuit is conditioned for non-automatic reclosing service, for winding 33 can never be energized so that every time arcing contacts 2 and 3 are operated a sequential opening of the isolating contacts 4 and 3 inevitably accompanies a circuit interrupting operation.

summarizing the above detailed explanation, it will be understood that the three sets of switch contacts controlled by the reclosing relay 33 operate in a predetermined sequence in which, firstly, the switch 31 opens to terminate the ilrst interrupting blast thereby permitting automatic reclosure of the interrupting contacts 2 and 3. Secondly, the interlock cut-oi! switch 33 opens to open-circuit the winding 33 so that interlock valve 33 can no longer prevent the sequential opening of the isolating contacts 4 and 3 in the event that a second interrupting blast occurs due to a continuation of the line fault. Thirdly, switch 63 closes to establish a closed shunt path around the already opened switch 31, thereby permitting a second interrupting blast which, in this case, is terminated by the auxiliary or cutoff switch 13 that opens in accordance with the accompanying opening of the isolating contact arm 3.

The pneumatic reclosing relay 33 comprises a plurality o! cylinders 11 and 13. A rather elaborate piston 13 is reciprocal in cylinder 11, while 8 an ordinary piston 33 is reciprocal in cylinder 13. Pistons 13 and 33 are interconnected by a plurality of links 3| and 32 and a lever 33 rotatable with a cam shaft 34. Link 32 connects piston 33 with one end of lever 33, while link 3| connects piston 13 with the other end of lever 33. With this arrangement the pistons 13 and 33 are interconnected so that when piston 13 is at the upper end of cylinder 11 piston 33 is at the bottom of cylinder 13. A spring 33 mounted in cylinder 13, thetension of which may be controlled by an adiustable means 33, normally biases the pistons 13 and 33 to the positions indicated in Fig. l. A certain amount of limited adjustment of the initial piston position is ai forded by link 32 which may comprise a screwed eye-bolt connection indicated at 31.

Specially constructed piston 13 includes a port 33 leading from the upper face oi the piston to an annular chamber 33 intermediate the ends of the piston. When fluid under pressure is admitted to cylinder 11 through restricting oriilce 33 the pressure builds up slowly in bore 33 and annular chamber 33 until it overcomes the opposing force of spring 33 before the piston 13 begins to move slowly downward with regulated speed. After a short initial slow speed travel, piston 13 uncovers a port 3| tapped in the side wall of cylinder 11 which is illustrated as con.

nected with an accumulator chamber 32. When annular chamber 33 is exposed to port 3| fluid u'nder pressure must `build up in lchamber 32 before further movement of piston 13 will take place. In certain cases it may be desirable to dispense with accumulator chamber 32 and merely provide an oriilce 3| to atmosphere in which case slower reclosing times are obtained. If faster reclosing times are desired port 3| may be dispensed with entirely. It is obvious that by providing an accumulator chamber the size of which may be varied, an orifice to atmosphere, or no port at all, widely varying travel-time characteristics of piston 13 may be secured.

In accordance with the disclosure of Fig. 1, at

approximately two-thirds of the stroke of piston 13 port 3| is again blocked or closed by the upper portion of piston 13 so that in the cases where accumulator chamber 32 or an oriilce to atmosphere is provided with a resulting hesitation of piston 13, speeding up of piston 13 then occurs to complete the piston stroke against the increasing force of return spring 33. 'Ihe function oi pneumatic reclosing relay 33 is to obtain an operating impulse from the iluid blast of the circuit breaker, which exists for a very short time such as a relatively few cycles of the alternating current of power line 23, and to give accurate and desired time control over a period of at least 60 cycles based only on the initial impulse. To this end pneumatic reclosing relay 33 is supplied with iluid under pressure from conduit 31 every time blast valve i3 is opened. In order that iiuid under pressure for operating pneumatic relay 33 may be available for a period comparable with the operating cycle of pneumatic relay 33 even though iluid under pressure in conduit 31 exists for a very small fraction of this period, a time delay reservoir 33 is provided which is connected between conduit 31 and conduit 34 connected to orifice 33 in cylinder 11. A check valve 33 prevents the escape of fluid from time delay reservoir 33 back through conduit 31. A check valve 33 also may be provided for preventing tluid from flowing back from conduit 34 into reservoirj93 if desired. Preferably time delay reservoir 98 is provided with an adjustable escape port 91. By proportioning the volume of time delay reservoir 93 and the size of escape port 91 the length of the cycle of pneumatic relay 86 can readily be controlled.

It will be understood that an operating cycle of pneumatic reclosing relay 66 consists of a downward stroke of the piston 19 followed by its return stroke under the influence of spring means 85, the physical limits being determined by the positioning of adjustable means 86 within cylinder 18. During this cycle of operation of pneumatic reclosing relay 66 shaft 84, which in eiect is a cam shaft, is rotated approximately 90 degrees from the position indicated in Fig. 1 to the position indicated in Fig. 2, and then returned to its initial position shown in Fig. 1 at which time the air pressure in time chamber or time delay reservoir 93 and in cylinder 11 has been dissipated.

In accordance with the four requirements specified for the recloslng relay of our invention,

switches 81, 68 and 69 must be operated in a predetermined sequence during the down stroke of piston 19k and in a different manner during the -up stroke of this piston. Accordingly we have illustrated switch 61 Ias pivotally mounted at 98 and biased to the closed position by means of a spring 99. Operation of switch 61 may be accomplished by a cam adjustably mounted on shaft a4 and rotatable therewith. It 1s desired that switch 61 be opened early in the cycle of pneumatical reclosing relay 66, say approximately two cycles after piston 19 begins to move or probably some five cycles after winding 36 of the overload relay is energized. The rise l0| of cam 00 is adapted to engage a roller |02 associated with pivotally mounted switch 61 so that when cam |00 rotates in a counterclockwise direction as viewed in Fig. l, roller |02 rises on cam surface |0| and switch 61 is opened.. Reclosing of switch 61 occurs at the end of the reverse stroke of piston 19 when roller |02 rides down the cam rise |0|. The arrangement described thus far performs the first requirement or the first function enumerated above for pneumatic relay 66.

In order to fulll the requirements of the second and third functions of pneumatic relay 66 mentioned above, it is desirable that switches 68 and 69 are actuated a few cycles later than the opening of switch 61, the switch 69 conveniently being opened during the closing movement of switch 68. Respecting the fourth function, by

arranging for the substantially simultaneous resetting of switches 61, 68 and 69 the reclosing circuits are restored to their original condition without hazard or loss of air that might result from a. false operation in the event that the breaker is switched closed before the completion of the resetting process. Accordingly, switches 68 and 69 must operate at a different point on the return stroke than that at which they operated on the down'stroke of piston 19. To accomplish this, switches 68 and 68 are mounted on a common support pivotally mounted at |03 which support is biased to the position indicated in Fig. 1 by spring means |04. Switches 68 and 69 are movable between contacts 16 and 16 so that they are in effect sequentially operable, the switch 69 opening before the switch 68 is closed, and the switch 68 opening before the switch 69 is closed. In accordance with our invention actuation of switches 68 and 69 is performed by a rockable prop-type cam |06 pivotally mounted at |06 to a fixed support |01. This cam has a large opening in the center thereof (not shown in the drawing) through which shaft 84 may extend and of such a size as to provide suilicient clearance around shaft 04 so that adequate pivotal movement of /cam |05 is permitted. When the cam 05 is rotated in a counter-clockwise direction from the position indicated in Fig. 1 to the position indicated in Fig. 2r it engages a roller |08 mounted on the pivotally mounted support for switches 68 and 69 and actuates the switches to the position indicated in Fig. 2 when the roller |08 moves upon the arcuate surface |09 of proptype cam |05 as is clearly shown in Fig. 2. 'I'he switches 68 and 69 remain in the position indicated in Fig. 2 until the prop cam |05 is brought back vto its original position at which moment the switch arm roller |08 drops off the prop cam surface |09. From the above description it will be obvious that either switch 61 or switch 68 is closed practically all o'f the time so that winding 32 is capable of being energized at any time there is trouble on the associated power line. Whether switch 61 or 66 is closed determines whether external switch blade 5 will be opened or not.

In order to actuate prop-type cam |05 at the proper time to open switch 69 and close switch 68 we provide a, cam ||0 adjustably mounted on cam shaft 84 and rotatable therewith. Cam ||0 is preferably similar to cam |00 described above. Cam ||0 is mounted closely adjacent to one side of prop-type cam |05 so that during rotation of cam shaft and cam i0 a roller i i on proptype cam |05 is engaged by cam ||l'| and when roller rides up the cam rise H2 of cam H0, as is indicated in Fig. 2, switches 66 and 69 are actuated to the positions indicated in Fig. 2, and are maintained in these positions due to the downhill curvature of cam surface |09 upon which roller |08 dwells even though cam ||0 were reversely rotated'and roller was free of the high point of operating cam H0. Cam ||0 is designated as the operating cam to distinguish it from a resetting cam ||3 that also is adjustably mounted on cam shaft 84 but closely adjacent the other side of prop-type cam |05 so that prop-type cam |05 is mounted between cams ||0 and ||3. Resetting cam ||3 is provided with a cam rise ||4 for engaging a roller ||5 mounted on prop-type cam |05 on the opposite side from where roller is mounted. When the cam shaft, including resetting cam ||3, is rotated in a clockwise direction as viewed in Fig. 2, the cam rise |4 engages roller I5 thereby rotating proptype cam |05 back to its original position so that switches 68 and 69 are reset to the positions indicated in Fig. 1. By properly positioning resetting cam i3 on cam shaft 84 relative to cam |06 the switches 61, 68 and 69 may be reset at approximately the same time near the end of the return stroke of piston 19.

The return stroke of pneumatic re'closing relay 66 is much slower than the pressure stroke for actually in accordance with the preferred embodiment of our invention all three switches 61, 68 and 69 have operated within about one-sixth of a second or 10 cycles while the resetting of these switches does not occur until approximately one minute or 60 cycles later, cycles referring to an alternating current flowing in power line 28 having a frequency of 60 cycles. The following table is representative of the sequential order of Operation of the various parts of an electric 1l circuit breaker constructed in accordance with our invention with reference to the time elapsed from the time of energization of overcurrent relay winding 36 for a typical reclosing operation:

Elapsed Time in Cycles l Operation oi Parts of Reclosing Breaker and Control Thereior Winding 36 energized Contacts 35 bridged Blast valve 18 opens Switch 69 opens. Switch 68 closes.. Circuit redosed through contacts 2 and 3 .Waverly-senape. ONUIONKOOCO IF FAULT PERSISTS Winding 36 reenergized Contacts 35 reclosed Blast valve 18 reopens Circuit re-interrupted in chamber 7. Isolating switch 5 opens T Auxiliary or blast cut-oi switch 70 opens- Blast valve 18 recloses Interruptor contacts 2 and 3 rec1ose Switches 67, 68 and 69 reset 1 Based on a 60 cycle per second system.

It will be understood that if after step aboveY the fault does not persist then steps 11 to 18 are eliminated and step 19 follows step 10.

In view of the detailed description included above the operation of the circuit breaker control arrangement including pneumatic reclosing relay 65 will be obvious to those skilled in the art. With the manual selector switch 13 inthe position indicated in Fig. 1 a reclosing trip operation of circuit breaker I is initiated in response to an abnormal current condition on power line 28 causing overload relay, including winding 38, to bridge contacts 35. Bridging of contacts 35 causes energization of blast valve winding 32 with the consequent opening of blast valve I8. At the same time winding 63 of isolating interlock valve 58 is also energized to close the passageway between conduits 51 and 59 whereupon switch opening valve 41 cannot be opened and consequently isolating or disconnecting contacts 4 and 5 remain closed. A blast of uid under pressure in response to opening of blast valve I8 separates arcing contacts 2 and 3 and interrupts the circuit in chamber 1. As soon as blast valve I8 is opened pneumatic reclosing relay 66 is supplied with fluid under pressure and begins to function in a sequence set forth by the above mentioned table. Switch 61 is rst opened to deenergize winding 32 whereupon the fluid blast is shut off and contacts 2 and 3 'reclose the circuit under the influence of springs s and 9, respectively. Reclosing relay 66 continues to complete its cycle by virtue of the fluid stored in time delay reservoir 93 and after several more cycles have elapsed switch E9 is opened to deenergize winding $3 and consequently to reopen isolating interlock valve 58. Subsequently switch 58 is closed to complete a supplementary circuit for A blast valve winding 32. sists then contacts 35 will again be bridged as soon as arcing contacts 2 and 3 reclose the circuit whereupon blast valve I8 will again be opened. This time, however, switch opening valve 41 is supplied with iiuid under pressure for interlock winding 63 is now open-circuited by the opened contact 69 of the pneumatic relay so that isolating contacts 4 and 5 are operated to the open If a system fault perposition, during whichopening movement the 4blast valve is cut of! by the opening of switch 10. Reclosing relay 63 continues to complete its cycle with the resetting of all the switches l1, 68 and 69 near the end oi the cycle.

I1' the fault were only a temporary fault then contacts 2 and 3 are not re-opened because no successive blast is initiated and pneumatic reclosing relay 68 completes its cycle without anv further operation of the contacts of circuit breaker I. It selector switch 13 is moved to engage contact 15, isolating contacts 4 and l are opened each time that arcing contacts 2 and 3 are opened although subsequent thereto, because coil 83 now is open-circuited so that the interlock valve 58 remains open in the position shown and cannot respond, even in the event that contacts 3l close, to prevent operation ot the switch open- 1118 valve 41.

The contacts 35 controlled by switch 64 prevent premature cut-oil' oi the fluid blast by switch 81 during an operation in which isolating switch or external switch blade 5 is operated. In the interest ci minimizing air or gas consumption, the blast valve is closed more quickly on reclosing operations than on those in which the isolating switch 5 operates. When solenoid 82 is not energized, contacts 65 remain closed, shunting switch 61 and maintaining blast valve winding 32 energized until auxiliary switch III opens. In this way a continuing blast of fluid is assured for maintaining the interrupting contacts open until external switch blade lis substantially open even though switch 31 might have been opened.

It will be apparent to those skilled in the art that our invention is not limited to the particular construction shown but that changes and modications may be made without departing from the spirit and scope of our invention, and we aim in the appended claims to cover all such changes and modifications.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In an electricA circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in an electric circuit, a source of iluid under pressure, means including a blast valve for suppling a blast of arc extinguishing iluid adjacent said arcing contacts to separate the same and interrupt the circuit, means responsive to an operating condition of said circuit for opening said blast valve and consequently said arcing contacts, means for opening said disconnecting contacts, an electrically controlled valve responsive to said operating condition of said circuit for rendering said means for operating said disconnecting contacts ineffective, time delay means responsive to the opening of said blast valve for causing said blast valve to reclose with the consequent reclosing of said arcing contacts, and means responsive to a continuance or recurrence of said operating condition and controlled by said time delay means for rendering said electrically controlled valve ineffective to prevent opening of said disconnecting contacts following a subsequent opening of said arcing contacts.

2. In an electric switch comprising a pair of relatively movable contacts connected to control an electric circuit, a source of iiuid under pressure, means including a normally closed valve connected to said source of fluid for causing relative separation of said contacts. means responsive to an operating condition of said circuit for reamaca-1 leasing fluid capable oi' actuating said valve fxtom said source, interference means responsive to said operating condition of said circuit for preventing said released fluid from actuating said valve, time delay means responsive to said release of fluid from said source for rendering said interference means ineffective after a predetermined delay, and means responsive to a continuance or recurrence of :aid operating condition and controlled by said time delay means for again releasing fluid from said source that is effective to open the valve of said ilrst mentioned means thereby causing relative separation of said contacts.

3. In an electric circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in an electric circuit, a source of fluid under pressure, a blast valve connected to said source, means responsive to an operating condition of said circuit for opening said blast valve, means for opening said disconnecting contracts, an electrically controlled valve responsive to said operating condition of said circuit for rendering said means for opening said disconnecting contacts ineffective, time delay means including a fluid operated piston responsive to the opening of said blast valve for causing said blast valve to reclose, and means responsive to a continuance or d recurrence of said operating condition and controlled by said time delay means for rendering said electrically controlled valve ineffective to prevent opening of said disconnecting contacts following a subsequent opening of said arcing contacts.

4. In an electric circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in an electric circuit, a source of fluid under pressure, means including a blast valve for suppling a blast of arc extinguishing fluid adjacent said arcing contacts to separate the same and interrupt the circuit. means responsive to an operating condition of said circuit for opening said blast valve and consequently said arcing contacts, means for opening said disconnecting contacts` an electrically controlled interlock valve responsive to said operating condition of said circuit for rendering said means for operating said disconnecting contacts ineffective, time delay means including a pair of pistons interconnected by a linkage mechanism and responsive to the opening of said blast valve for causing said blast valve to reclose with the consequent reclosing of said arcing contacts, and means responsive to a continuance o r recurrence of said operating condition and controlled by said time delay means for rendering said means for opening said disconnecting contactseffective to open said disconnecting contacts following a subsequent opening of said arcing contacts.

' 5. In an electric circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in an electric circuit, a source of fluid under pressure, a blast valve connected to said source, means responsive to an operating condition of said circuit for opening said blast valve, means for opening said disconnecting contacts, an electrically controlled valve responsive to said operating condition of said circuit for rendering said means for opening said disconnecting contacts ineffective, time delay means including cam operated switches controlled by a fluid operated piston responsive to the opening of said blast valve for causing said blast valve trolled by one of said cam operated switches for rendering said electrically controlled valve ineffective to prevent opening of said disconnecting contacts following a subsequent opening of said arcing contacts.

6. In an electric switch comprising a pair of relatively movable contacts connected to control an electric circuit, a source of fluid under pressure, a fluid motor for producing relative movement between said contacts, a valve for con- A trolling the flow of fluid between said source and said fluid motor, means responsive to an operating condition of said circuit for releasing fluid from said source capable of causing operation of said valve, and a normally open interlock valve arranged to close in response to said operating condition of said circuit for preventing the released fluid from actuating said valve for a predetermined time after the occurrence of said operating condition.

7. In an electric circuit breaker comprising cooperating arcing contacts and a disconnecting switch serially connected with said arcing contacts in an electric circuit, a source of fluid under pressure, means including a blast valve for supplying a blast of arc extinguishing fluid adjacent said arcing contacts to separate the same and interrupt the circuit, means responsive to an operating condition of said circuit for opening said blast valve and consequently said arcing contacts, a fluid motor for opening said disconnecting switch, a switch controlling valve f or controlling the flow of fluid between said source and said fluid motor, an electrically controlled interlock valve responsive tov said operating condition of said circuit for rendering said switch controlling valve ineiective to supply fluid to said fluid motor to open said disconnect switch, time delay means including a pair of pistons interconnected by a linkage mechanism and responsive to the opening of said blast valve for causing said blast valve to' reclose with the consequent reclosing of said arcing contacts, and means responsive to a continuance or recurrence of said operating condition and controlled by said time delay means for rendering said interlock valve inoperative thereby rendering said switch controlling valve effective to cause said disconnecting switch to open folowing a subsequent opening of said arcing contacts.

8. In an electric switch comprising a. pair of relatively movable contacts connected to control an electric circuit, a source of fluid under pressure, a fluid motor for producing relative movement between said contacts, a switch controlling valve for controlling the flow of fluid between said source and said fluid motor, means responsive to an operating condition of said circuit for releasing energy capable of causing operation of said valve, and means responsive to said operating condition oi' said circuit for preventing the application of said released energy to said switch controlling valve for a predetermined time after the occurrence of said operating condition.

9. In combination with an electric circuit breaker having a pair of interrupting contacts and a pair of serially connected isolating contacts, means for controlling the operation of said interrupting contacts and said isolating contacts in a, predetermined sequence, comprising a pneumatic motor having a piston and associated cylinder, a cam shaft connected to said piston and rotatable upon movement of said piston, means including an annular chamber defined by said piston and cylinder for delaying the initial movement of said piston, a fluid reservoir in ccmmunication with said cylinder through an opening therein intermediate the ends thereof, said reservoir being effective while said chamber and said opening are in registry to slow down the operating movement of said piston after said initial movement thereof, means controlled by the position of said cam shaft for regulating the sequential operation of said isolating and said interrupting contacts, and means for controlling the supply of fluid under pressure to said motor to control the operation thereof.

10. In combination with an electric circuit breaker having a pair of interrupting contacts and a pair of serially connected isolating contacts, means for controlling the operation of said interrupting contacts and said isolating contacts in a predetermined sequence, comprising a pneumatic motor having a piston and associated cylinder, means connected to said piston and operable in response to movement of said piston to regulate the sequential operation of said interrupting contacts and said isolating contacts, means including an annular recess in said piston for delaying the movement of said piston during the initial portion of an operating stroke, means defining an opening in said cylinder for slowing down said piston when said recess registers with said opening during a subsequent portion of the operating stroke of said piston, and means for controlling the supply of fluid under pressure to said motor to control the operation thereof.

11. In combination with an electric circuit breaker having a pair of interrupting contacts and a pair of serially connected isolating contacts, means for controlling the operation of said interrupting contacts and said isolating contacts in a predetermined sequence, comprising fiuid operated means, a cam shaft connected to said fluid operated means and rotatable in response to operation of said fluid operated means, a plurality of cams on said cam shaft, a plurality of switches operated by said cams in a predetermined sequence for one direction of rotation of said cam shaft, means for substantially simultaneously resetting said switches during the other direction of rotation of said cam shaft, means controlled by said switches for controlling the sequential operation of said interrupting and said isolating contacts, and means for controlling the supply of fluid under pressure to said nuid operated means to control the operation thereof.

12. In combination with an electric circuit breaker having a pair of interrupting contacts and a pair of serially connected isolating contacts, means for controlling the operation of said interrupting and said isolating contacts, comprising uid operated means, a cam shaft connected to said fluid operated means and rotatable in response to operation of said fluid operated means, a first cam on said cam shaft, a first switch operated by said nrst cam, a second switch, a second cam having limited pivotal movement relative to said cam shaft for controlling said second switch, a pair of cams fixedly mounted on said cam shaft closely adjacent said second cam, one of said pairof cams rendering said second cam effective to operate in a particular manner said second switch for one direction of rotation of said cam shaft, the other of said pair of cams rendering said second cam effective to operate in a reverse manner said second switch, said cams being so arranged on said cam shaft that said first and second switches are operated in a predetermined sequence for one direction of rotation of said cam shaft and substantially simultaneously operated for the other direction of rotation of said cam shaft, means controlled by said switches for controlling the sequential operation of said interrupting and said isolating contacts, and means for controlling the supply of fluid under pressure fo said fluid operated means to control the operation thereof.

13. In combination with an electric circuit breaker having a pair of interrupting contacts and a pair of serially connected isolating contacts, means for controlling the operation of said interrupting contacts and said isolating contacts in a predetermined sequence, comprising fluid operated means, a cam shaft connected to said nuid operated means and rotatable in response to operation of said fluid operated means, a first cam on said cam shaft, a first switch operated by said nrst cam, a second switch, a second cam having limited pivotal movement relative to said cam shaft for controlling said second switch, a pair of cams flxedly mounted on said cam shaft closely adjacent said second cam, one of said pair of cams rendering said second cam effective to open said second switch for one direction of rotation of said cam shaft, the other of said pair of cams rendering said second cam effective to close said second switch, said cams being so arranged on said cam shaft that said first and second switches are opened in a predetermined sequence for one direction of rotation of said cam shaft and substantially simultaneously closed for the other direction of rotation of said cam shaft, means controlled by said switches for controlling the sequential operation of said interrupting and said isolating contacts, and means for controlling the supply of fluid under pressure fo said fluid operated means to control the operation thereof.

" ALEXANDER. C. BOIBBEAU.

JOHN W. BEATTY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,067,064 Platz Jan. 5, 1937 2,213,658 Thommen Sept. 3, 1940 2,240,803 Schiesser --.c May 6, 1941 2,275,885 Bartlett Mar. 10, 1942 2,287,041 `fourneau June 23, 1942 FOREIGN PATENTS Number Country Date 214,636 Great Britain Nov. 6. 1924 

